Hackers Bypass Gmail, Yahoo 2FA at Scale

A new Amnesty International report explains how cyberattackers are phishing second-factor authentication codes sent via SMS.

Amnesty International this week released a report detailing how hackers can automatically bypass multifactor authentication (MFA) when the second factor is a text message, and they're using this tactic to break into Gmail and Yahoo accounts at scale.

MFA is generally recommended; however, its security varies depending on the chosen factor. Consumers prefer second-factor codes sent via text messages because they're easy to access. Unfortunately for some, cybercriminals like them for the same reason.

Amnesty discovered several credential phishing campaigns, likely run by the same attacker, targeting hundreds of individuals across the Middle East and North Africa. One campaign went after Tutanota and ProtonMail accounts; another hit hundreds of Google and Yahoo users. The latter was a targeted phishing campaign designed to steal text-based second-factor codes.

Throughout 2017 and 2018, human rights defenders (HRDs) and journalists from the Middle East and North Africa shared suspicious emails with Amnesty, which reports most of this campaign's targets seem to come from the United Arab Emirates, Yemen, Egypt, and Palestine.

Most targets initially receive a fake security alert warning them of potential account compromise and instructing them to change their password. It's a simple scheme but effective with HRDs, who have to be on constant high alert for physical and digital security.

From there, targets are sent to a convincing but fake Google or Yahoo site to enter their credentials; then they are redirected to a page where they learn they've been sent a two-step verification code. Entering the code presents them with a password reset form. Most people wouldn't question a password change prompt from Google as it seems legitimate.

Attackers automate the full process: getting victims to log into their email accounts, obtaining the two-factor code, and prompting them to change their passwords.

It's worth noting text-based authentication is mostly unsafe for high-risk people because attackers have to pick a specific target. For corporate leaders and other folks holding sensitive data, it's worth exploring stronger methods of MFA, such as physical security keys.

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